33 Key JS Concepts
1.1. Call Stack
Mechanism or structure which interpreter keeps track of functions that are called
2.2. Primitive Types
Data type except object which is immutable.
3.3. Accesing by value and references
One rule: in-memory value is copied.
4.4. Type Coercion
Type coercion is converting a value from one type to another.
5.5. ==, ===, typeof, instaceof
Checking Data type is not easy in Javascript.
6.6. Function Scope, Block Scope and Lexical Scope
- Functions are executed when they are called/invoked. - Functions always returns value. If value isn't given, it returns `undefined`. - Functions are
7.7. Expression vs Statement
Function declarations are hoisted, but function expressions aren't.
8.8. IIFE, Modules, and Namespaces
IN ES6, built-in modules were finally introduced. Before ES6, developers used external libraries like CommonJS for modules.
9.9. Message Queue and Event Loop
How is Javascript asynchronous and single-threaded in same time?
10.10. setTimeout, setInterval, and requestAnimationFrame
setTimeout, setInterval, and requestAnimationFrame are 3 most common APIs for scheduling call.
11.11. JavaScript Engines
JS engine is a program that converts JS code into lower level or machine code that microprocessors can understand.
12.12. Binary Expression, Bitwise Operator
Bits are binary digits consists of 0 & 1, which is the basic unit of data in computer.
13.13. DOM and Layout Trees
Everything in HTML source code in included in DOM and represented as an node(object).
14.14. Factories and Classes
In Javascript, there are two ways for creating objects; factories and classes.